/**
 * Copyright (c) 2011-2023, James Zhan 詹波 (jfinal@126.com).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jfinal.template.stat.ast;

import java.util.List;
import com.jfinal.template.Env;
import com.jfinal.template.TemplateException;
import com.jfinal.template.io.Writer;
import com.jfinal.template.stat.Ctrl;
import com.jfinal.template.stat.Scope;

/**
 * StatList
 */
public class StatList extends Stat {

    public static final Stat NULL_STAT = NullStat.me;
    public static final Stat[] NULL_STAT_ARRAY = new Stat[0];

    private Stat[] statArray;

    public StatList(List<Stat> statList) {
        if (statList.size() > 0) {
            this.statArray = statList.toArray(new Stat[statList.size()]);
        } else {
            this.statArray = NULL_STAT_ARRAY;
        }
    }

    /**
     * 持有 StatList 的指令可以通过此方法提升 AST 执行性能
     * 1：当 statArray.length >  1 时返回 StatList 自身
     * 2：当 statArray.length == 1 时返回 statArray[0]
     * 3：其它情况返回 NullStat
     *
     * 意义在于，当满足前面两个条件时，避免掉了 StatList.exec(...) 方法中的判断与循环
     */
    public Stat getActualStat() {
        if (statArray.length > 1) {
            return this;
        } else if (statArray.length == 1) {
            return statArray[0];
        } else {
            return NULL_STAT;
        }
    }

    public void exec(Env env, Scope scope, Writer writer) {
        Ctrl ctrl = scope.getCtrl();
        for (int i=0; i<statArray.length; i++) {
            if (ctrl.isJump()) {
                break ;
            }
            statArray[i].exec(env, scope, writer);
        }
    }

    public int length() {
        return statArray.length;
    }

    public Stat getStat(int index) {
        if (index < 0 || index >= statArray.length) {
            throw new TemplateException("Index out of bounds: index = " + index + ", length = " + statArray.length, location);
        }
        return statArray[index];
    }
}


